This invention relates generally to injection molding and more particularly to a heated nozzle having a tube for removably receiving a thermocouple element extending along the inner surface of a cylindrical locating flange where it is spaced from the outer surface of the central portion of the nozzle.
Mounting a heated injection molding nozzle in a well in a cooled mold with an insulative air space between them is well known. It is also known to run a thermocouple element through the air space to monitor the operating temperature near the forward end of the nozzle. An example of this is shown in the applicant's U.S. Pat. No. 4,583,284 which issued Apr. 22, 1986 where the thermocouple element extends into the insulative air space through an opening in the mold. Another example is seen in the applicant's U.S. Pat. No. 4,768,283 which issued Sep. 6, 1988 where the thermocouple element extends into the insulative air space through a thermocouple bore extending forwardly through the rear collar portion of the nozzle. While these previous configurations are usually satisfactory, they have the danger that in the event of a leak of pressured melt into the air space, the melt will flow out of the air space along the thermocouple element and fill the electrical wire channels in the mold. The resulting plastic spread throughout the mold is very difficult to remove when the mold has to be disassembled.
U.S. Pat. No. 4,705,473 to Schmidt which issued Nov. 10, 1987 shows an arrangement which avoids this problem by extending the thermocouple bore entirely through the nozzle and not entering the insulative air space around it. However, this configuration has the disadvantage that it is more difficult to make and is not possible when the nozzle diameter is reduced to produce compact nozzles.